JP2007175834A - Wafer chamfering device and wafer chamfering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer chamfering device and a wafer chamfering method, confirming the presence/absence of abnormality in a notch grinding wheel without a mistake by using an abnormality detecting sensor having a simplified mechanism. <P>SOLUTION: The abnormality detecting sensor 1 is positioned in the vicinity of a notch precise grinding wheel 58 or a notch rough grinding wheel 61 of the chamfering device 10, and adapted to confirm the presence/absence of a grinding wheel depending on a change in back pressure of injected air. Abnormality such as break, slip-off or deformation caused in the notch grinding wheel is confirmed by the sensor 1 without wrong detection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer chamfering apparatus and a wafer chamfering method for chamfering an outer peripheral portion of a wafer, which is a material of a semiconductor device or an electronic component.

  A wafer such as silicon, which is a material for semiconductor devices and electronic components, is sliced from the ingot state with a slicing device such as an inner peripheral blade or a wire saw, and then the outer peripheral portion is prevented to prevent cracking or chipping of the peripheral edge. Chamfering is applied to The chamfering apparatus used for the chamfering process includes a grindstone for grinding the outer circumference of the wafer and a grindstone for notching which grinds a V-shaped notch portion (N portion shown in FIG. 9) serving as a reference position for the orientation. A plurality of grindstones such as these are attached, and these grindstones are processed at high speed by a spindle.

  However, in such a chamfering device, the grindstone may be damaged or deformed due to deterioration due to long-term use, overload during grinding, or the like. Normally, in various processing of wafers, a large number of wafers are stored in one cassette and processed continuously automatically. If such a problem occurs during processing, it cannot be detected. Processing is continued as it is, and many wafers are wasted.

  For this reason, for example, for detecting a problem occurring in the grindstone, the load applied to the grindstone is detected from the change in the current value of the motor that rotates the grindstone, and the chamfering device is controlled by checking whether there is an abnormality in the grindstone. A chamfering method and a chamfering apparatus have been proposed (see, for example, Patent Document 1).

In addition, as another method for confirming an abnormality, a method of providing an optical sensor or a proximity sensor in the vicinity of the grindstone, or confirming the presence or absence of an abnormality such as breakage, deformation, or dropout of the grindstone by image processing or the like is also implemented.
JP-A-8-236486

  However, when the presence or absence of an abnormality in the grindstone is confirmed by the technique proposed in the above-mentioned patent document, the setting of values for discriminating between the normal state and the abnormal state is the surrounding environment, the type of wafer, the rotational speed of the grindstone, etc. Therefore, it is difficult to adjust the value, and many people misunderstand it.

  Also, in other methods, cutting fluid and grinding debris are scattered around the processing point, the measurement environment is poor, it is difficult to confirm by light or video, and it is easy to be erroneously recognized. In addition, since discrimination by magnetism is also determined depending on the material of the grindstone, measurement is performed at a place other than the grindstone, such as a grindstone holder, resulting in poor measurement accuracy. Further, in the image processing apparatus or the like, the price of the apparatus is expensive, and a great expense is required for installation.

  The present invention has been made to solve such a problem, and a wafer chamfering apparatus and a wafer chamfering device capable of confirming the presence or absence of abnormality of a notch grindstone without erroneous recognition by a simple mechanism abnormality detection sensor. It aims to provide a method.

  In order to achieve the above object, the present invention provides a wafer table for holding a wafer, one or more grindstones for grinding an outer peripheral portion of the wafer, and a notch portion of the wafer. A notch grindstone, a moving means for moving the wafer table relative to the grindstone and the notch grindstone, located near the notch grindstone, and a change in back pressure of air to be injected An abnormality detection sensor for confirming the presence or absence of abnormality of the notch grindstone is provided.

  According to the first aspect of the invention, the wafer held and rotated by the wafer table and the outer peripheral grinding wheel rotating at high speed are relatively moved by the moving means, and the wafer outer peripheral part is ground. Subsequently, the notch portion of the wafer and the notch grindstone rotating at high speed are relatively moved by the moving means, and the notch portion is ground.

  At this time, an abnormality detection sensor for injecting air toward the notch grindstone located above is provided in the vicinity of the notch grindstone in the vertical direction. In the abnormality detection sensor, the back pressure of the air to be injected is confirmed before the machining of the notch portion by the notch grindstone.

  As a result, when the notch grindstone is damaged, dropped, or deformed, the injected air passes without hitting the notch grindstone, so the back pressure is lowered and it is possible to detect an abnormality in the notch grindstone. Become. When an abnormality is detected, the chamfering device is stopped and processing is not started, so that processing defects and unprocessed parts do not occur on the wafer, and the wafer is not wasted.

  Moreover, since air is always ejected from the abnormality detection sensor, the sensor is not disabled by cutting fluid or cutting waste, and stable and highly accurate detection without erroneous detection can be performed.

  According to a second aspect of the present invention, in the first aspect of the invention, the abnormality detection sensor includes an air sensor portion that injects air toward the notch grindstone, and an arm member provided with the air sensor portion at one end. And a support member that supports the arm portion.

  According to the invention of claim 2, the abnormality detection sensor is provided with an air sensor part having a nozzle from which air is ejected provided at one end of an arm part supported by a support member having elastic force, and is located above. Air is blown out toward the notch grinding wheel.

  Thereby, the abnormality detection sensor is provided in the vicinity of the notch grindstone by a simple and inexpensive mechanism. In addition, since air is constantly being jetted from the air sensor, cutting fluid and cutting waste rarely enter the measurement location, so it is possible to check for abnormalities in the notch grindstone without being affected by the environment. It becomes. Furthermore, maintenance is good because the mechanism is simple.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the abnormality detection sensor moves the wafer table by the moving means and grinds the notch portion of the wafer with the notch grindstone. At this time, the pressing portion provided on the arm portion is pressed by the wafer table, the support member is elastically deformed, and the air sensor portion is retracted from the vicinity of the notch grindstone.

  According to the third aspect of the present invention, the pressing portion provided on the arm portion of the abnormality detection sensor holds the wafer approaching the notch grindstone when the notch portion of the wafer is ground by the notch grindstone. It is pressed by. When the support member is elastically deformed and the wafer table moves to the processing position of the notch part, the air sensor part of the abnormality detection sensor is completely retracted from the vicinity of the notch grindstone.

  Thereby, even if there is no separate movement mechanism, the abnormality detection sensor can be easily moved to a position that does not hinder the processing of the notch portion.

  According to a fourth aspect of the present invention, in any one of the first, second, and third aspects, the support member has an elastic force and has a cross shape in which two planes intersect. Yes.

  According to the invention of claim 4, the support member is formed in a cross shape in which two plate-like elastic bodies intersect.

  As a result, when the abnormality detection sensor is pressed by the wafer table and the support member is elastically deformed, unlike the one plate-like member or rod-like member, the displacement in the torsional direction does not occur, and the air sensor portion of the abnormality detection sensor It is possible to move while always maintaining a vertical state. Thereby, stable and highly accurate detection without erroneous detection can be performed.

  According to a fifth aspect of the present invention, in any one of the first, second, third, and fourth aspects, the abnormality detection sensor is configured to detect the abnormality due to a change in back pressure when retracted from the vicinity of the notch grindstone. It is characterized by checking the presence or absence of abnormality of the detection sensor itself.

  According to the invention of claim 5, the abnormality detection sensor that is pressed by the wafer table and retracted from the vicinity of the notch grindstone prevents the clogging of the nozzle from which the air is injected by the cutting fluid or cutting waste, so that the air is always supplied. Continue to spray. At this time, since the jetted air does not hit the notch grindstone, the back pressure of the jetted air decreases. However, when the back pressure does not change due to malfunctions in the piping, nozzles, sensors, etc. of the abnormality detection sensor, the chamfering device is stopped as an abnormality of the abnormality detection sensor itself.

  Accordingly, it is possible to confirm the abnormality of the notch grindstone without erroneous recognition without continuously confirming the abnormality of the notch grindstone in a state where the abnormality detection sensor is defective.

  According to a sixth aspect of the present invention, the notch is formed by changing a back pressure of air to be sprayed in the vicinity of a notch grindstone of a wafer chamfering apparatus that holds a wafer by a wafer table and grinds an outer peripheral portion and a notch portion of the wafer. An abnormality detection sensor for confirming whether there is an abnormality in the grinding wheel is retractable from the vicinity of the notch grinding wheel, and before the grinding of the notch portion of the wafer, the abnormality detection sensor confirms the presence of abnormality in the notch grinding stone Then, when grinding the notch portion of the wafer, the abnormality detection sensor is pressed by the wafer table and retracted from the vicinity of the notch grindstone to check whether the abnormality detection sensor itself is abnormal. It is characterized by.

  According to the sixth aspect of the present invention, an abnormality detection sensor is provided in the vicinity of the notch grindstone of the wafer chamfering apparatus for confirming whether the notch grindstone is abnormal due to a change in the back pressure of the sprayed air. When the notch portion of the wafer is ground, the abnormality detection sensor is pressed by the wafer table, the support member is elastically deformed, and retracts from the vicinity of the notch grindstone. At this time, the abnormality detection sensor checks whether or not there is an abnormality from the change in the back pressure.

  As a result, when the notch grindstone is damaged, dropped, or deformed, the back pressure is lowered and it is possible to detect an abnormality of the notch grindstone. Further, when the abnormality detection sensor is retracted from the vicinity of the notch grindstone, if the back pressure does not decrease, it can be detected as an abnormality of the abnormality detection sensor.

  As described above, according to the wafer chamfering apparatus and the wafer chamfering method of the present invention, it is a simple and inexpensive mechanism by air, and the maintenance-free abnormality detection sensor breaks the notch grindstone without erroneous recognition. It is possible to confirm whether there is an abnormality such as dropout or deformation.

  Preferred embodiments of a wafer chamfering apparatus and a wafer chamfering method according to the present invention will be described below in detail with reference to the accompanying drawings.

  First, a wafer chamfering apparatus according to the present invention will be described. FIG. 1 is a front view showing a main part of the chamfering apparatus.

  The chamfering apparatus 10 includes a wafer feeding unit 20, a grindstone rotating unit 50, a wafer supply / storage unit (not shown), a wafer cleaning / drying unit, a wafer transfer unit, and a controller that controls operations of each part of the chamfering device.

  The wafer feeding unit 20 includes an X-axis base 21, two X-axis guide rails 22, 22, four X-axis linear guides 23, 23,..., A ball screw and a stepping motor mounted on the main body base 11. It has an X table 24 that is moved in the X direction in the figure by an X axis driving means 25 that is a linear movement axis.

  The X table 24 has two Y-axis guide rails 26, 26, four Y-axis linear guides 27, 27,..., And a Y-axis drive means that is a linear movement shaft composed of a ball screw and a stepping motor (not shown). A Y table 28 that is moved in the Y direction is incorporated.

  The Y table 28 is guided by two Z-axis guide rails 29 and 29 and four Z-axis linear guides (not shown), and is shown by a Z-axis drive means 30 which is a linear movement shaft composed of a ball screw and a stepping motor. A Z table 31 that is moved in the Z direction is incorporated.

  The Z table 31 incorporates a θ-axis motor 32 and a θ spindle 33, and a wafer table (mounting table) 34 on which the wafer W is sucked and mounted is attached to the θ spindle 33, and the wafer table 34 rotates the wafer table. It is rotated around the axis CW in the θ direction in the figure.

  A truing grindstone 41 (hereinafter referred to as a truer 41) used for truing a grindstone for chamfering the peripheral edge of the wafer W is attached to the lower portion of the wafer table 34 concentrically with the wafer table rotation axis CW.

  By the wafer feeding unit 20, the wafer W and the truer 41 are rotated in the θ direction in the figure and are moved in the X, Y, and Z directions.

  The grindstone rotating unit 50 is mounted with an outer peripheral grindstone 52, and is mounted on an outer grindstone spindle 51 that is driven to rotate about an axis CH by an outer grindstone motor (not shown), and a turntable 53 disposed above the outer peripheral grindstone 52. The outer peripheral fine spindle 54 and the outer peripheral fine spindle motor 56, the notch rough spindle 60 and the notch coarse motor 62, the notch fine spindle 57 and the notch fine motor 59 are provided. In the vicinity of the notch coarse spindle 60 and the notch fine spindle 57, the abnormality detection sensors 1 for confirming abnormality such as breakage, dropout, or deformation of the grindstone are provided on the support columns 8, respectively.

  The outer peripheral fine spindle 54 is inclined (8 degrees in this embodiment) with the rotation axis in the tangential direction of the wafer W (X-axis direction shown in FIG. 1). A peripheral grinding wheel 55 which is a chamfering grindstone for finish grinding the outer circumference of the wafer W is attached to the peripheral grinding spindle 54.

  A notch rough grinding wheel 61 is attached to the notch rough spindle 60, and a notch fine grinding wheel 58, which is a chamfering grind for grinding the notch portion, is attached to the notch fine spindle 57. The notch precision grinding wheel 58 is held so as to be inclined by a predetermined amount in an arbitrary direction.

  FIG. 2 shows a truer 41 attached to the wafer table 34. As shown in FIG. 2, the truer 41 is attached to the lower part of the wafer table 34 concentrically with the wafer table rotation axis CW and is rotated θ by the θ-axis motor 32. Further, the upper surface of the wafer table 34 is a suction surface that communicates with a vacuum source (not shown), and a wafer W to be chamfered is placed and fixed by suction.

  FIG. 3 shows the configuration of the outer peripheral processing grindstone 52. The outer peripheral processing grindstone 52 has a two-stage configuration, the lower stage is a master grindstone 52A having a master groove 52a that forms the outer peripheral shape of the truer 41, and the upper stage is an outer peripheral rough grind groove 52b for forming a wafer W. It is a grinding wheel 52B.

  In order to simplify the description in FIG. 3, one grindstone is described for each grindstone. However, in order to cope with the deformation of the groove shape due to wear, a plurality of grindstones are provided for each grindstone. Grooves are formed.

  FIG. 4 shows the abnormality detection sensor 1 provided in the vicinity of the notch coarse spindle 60 and the notch fine spindle 57. In the abnormality detection sensor 1, an arm member 2 is attached to a base 4 provided on a support column 8 with a support member 3 formed in a cross shape by an elastic body made of metal or resin.

  At one end of the arm member 2, an air sensor unit 6 provided with an air jet port 6A is attached upward. A tube 7 is connected to the air sensor unit 6, and air is sent from an air supply source (not shown) via a pressure sensor 9 and a regulator 12 as shown in FIG. The sent air is injected from the injection port 6A toward the notch fine grinding wheel 58 or the notch coarse grinding wheel 61, and the back pressure of the injected air is detected by the pressure sensor 9.

  At this time, if the notch fine grinding wheel 58 or the notch coarse grinding wheel 61 has an abnormality such as breakage, dropout, or deformation, the back pressure detected by the pressure sensor 9 decreases. When the back pressure falls below a preset value, the chamfering device 10 is stopped by a control device (not shown).

  On the side surface of the arm member 2, a pressing member 5 made of a wear-resistant resin is provided toward the wafer table 34. As shown in FIG. 5, the pressing member 5 is pressed in contact with the approaching wafer table 34 when the notch portion N of the wafer W is ground by the notch fine grinding wheel 58 or the notch rough grinding wheel 61.

  Thereby, the support member 3 which is an elastic body bends and the arm member 2 moves. At this time. Since the support member 34 is a cross-shaped elastic body, no twist or the like occurs and the arm member 2 moves in parallel.

  As the arm member 2 moves, the air sensor unit 6 retreats from below the notch fine grinding wheel 58 or the notch coarse grinding wheel 61, and the injected air hits the notch fine grinding wheel 58 or the notch coarse grinding wheel 61. Instead of spraying upward.

  At this time, if the back pressure of the injected air detected by the pressure sensor 9 has not decreased, the chamfering device 10 is stopped by a control device (not shown) assuming that the abnormality detection sensor 1 itself has an abnormality.

  When the grinding of the notch portion N is finished and the wafer table 34 is separated, the pressing member 5 is not pressed and the arm member 2 is moved in parallel to return to the original position, and the air sensor portion 6 is also moved to the notch precision grinding wheel 58 or notch. Return to the lower vicinity of the rough grinding wheel 61.

  In the present embodiment, the truer 41 has an outer diameter equal to or smaller than that of the wafer W to be processed, and uses a disk-shaped GC (Green silicon carbide) grindstone or a WA (White fused aluminum) grindstone with the same thickness. The particle size of the grindstone is # 320.

  The master grindstone 52A was a diamond bonded metal bond grindstone with a diameter of 202 mm and had a particle size of # 600. The outer peripheral rough grinding wheel 52B is a diamond bonded metal bond grindstone having a diameter of 202 mm and a particle size of # 800.

  The peripheral grinding wheel 55 is a resin bond grindstone of diamond abrasive grains having a diameter of 50 mm, and has a particle size of # 3000. Further, the notch rough grinding wheel 61 has a small diameter of 1.8 mm to 2.4 mm, a diamond bond metal bond grindstone, grain size # 800, and the notch fine grinding wheel 58 has a diameter of 1.8 mm to 2.4 mm. A resin bond grindstone of diamond abrasive grains, grain size # 4000 is used.

  The outer peripheral grinding wheel spindle 51 is a built-in motor driven spindle using a ball bearing and is rotated at a rotational speed of 8,000 rpm. Further, the outer peripheral precision spindle 54 is a built-in motor driven spindle using an air bearing and is rotated at a rotational speed of 35,000 rpm.

  The notch rough spindle 60 is an air turbine driven spindle using an air bearing and is rotated at a rotational speed of 80,000 rpm. The notch precision spindle 57 is a built-in motor driven spindle using an air bearing and has a rotational speed of 150, Rotated at 000 rpm.

  Since the other components of the chamfering device 10 are generally well-known mechanisms, a detailed description is omitted.

  Next, the wafer chamfering method according to the present invention will be described with reference to the flowchart showing the chamfering method of FIG.

  In the chamfering device 10, truing is first performed on the outer peripheral grinding wheel 55 and the notch precision grinding wheel 58 using the truer 41 processed into the target chamfered shape by the master grinding wheel 52 </ b> A of the outer circumferential grinding wheel 52.

  After grooves for chamfering are formed on each grindstone by truing, the wafer W is placed on the wafer table 34 and chamfering is started (step S1).

  In the chamfering process, the outer periphery of the wafer W is first roughly ground by the outer periphery rough grinding wheel 52B of the outer periphery processing grindstone 52. When the outer peripheral rough grinding of the wafer W is completed, the X table 24, the Y table 28, and the Z table 31 are moved so that the wafer W is aligned with the processing position of the outer peripheral grinding wheel 55. Is started (step S2).

  When the outer peripheral precision grinding of the wafer W is completed, the Y table 28 is returned and the wafer W is separated from the outer peripheral precision grinding wheel 55. Subsequently, the turntable 53 rotates to move the notch rough grinding wheel 61 to a position where the notch N is processed, and the Z table 31 moves the wafer W to the processing position of the notch rough grinding wheel 61 in the Z direction.

  When the wafer W moves to the processing position of the notch rough grinding wheel 61, the back pressure of the air injected from the air sensor unit 6 toward the notch rough grinding wheel 61 is detected by the pressure sensor 9 shown in FIG. It is confirmed by a control device (not shown) (determination C1).

  If the confirmed back pressure of the air is less than or equal to a preset specified value, the control device determines that the notch rough grinding wheel 61 has an abnormality such as breakage, dropout, or deformation, and chamfers. The apparatus 10 is stopped. After the chamfering apparatus 10 stops, the abnormal notch rough grinding wheel 61 is replaced and the operation of the chamfering apparatus 10 is restarted (step S3).

  If the confirmed back pressure of the air is equal to or greater than a predetermined value set in advance, it is determined that the notch rough grinding wheel 61 has no abnormality, and rough grinding of the notch N is started by the notch rough grinding wheel 61 (step S4).

  At this time, the abnormality detection sensor 1 starts from the state shown in FIG. 7A, as shown in FIG. 7B, the pressing member 5 comes into contact with the approaching wafer table 34, the support member 3 is bent, and the arm 3 is bent. The member 2 moves. As a result, the air sensor unit 6 retracts from the vicinity of the notch rough grinding wheel 61 in the vertical direction, and the injected air does not hit the notch rough grinding wheel 61. The back pressure of the air that no longer hits the notched rough grinding wheel 61 is detected by the pressure sensor 9 shown in FIG. 6 and is confirmed by a control device (not shown) (determination C2).

  When the confirmed back pressure of the air is not changed compared to the back pressure when the air hits the notch rough grinding wheel 61, the control device determines that a failure has occurred in the abnormality detection sensor 1. After the processing of the wafer W being processed, the chamfering device 10 is stopped. After the chamfering apparatus 10 is stopped, the location where the defect has occurred is repaired and replaced, and the operation of the chamfering apparatus 10 is resumed (step S5).

  When the confirmed back pressure of the air is changed as compared with the back pressure when the air hits the notch rough grinding wheel 61, the control device determines that the abnormality detection sensor 1 is operating normally. Then, after the machining with the notch rough grinding wheel 61 is finished, the fine grinding of the notch N with the notch fine grinding wheel 58 is started (step S6).

  In the fine grinding of the notch N by the notch fine grinding wheel 58, as in the case of the rough grinding by the notch rough grinding stone 61, the presence or absence of abnormality of the notch fine grinding wheel 58 is confirmed before processing. When it is determined that an abnormality such as breakage, dropout, or deformation has occurred, the chamfering device 10 is stopped and the notch precision grinding wheel 58 is replaced.

  When it is determined that there is no abnormality, fine grinding of the notch N by the notch fine grinding wheel 58 is started, whether or not the abnormality detection sensor 1 is abnormal is confirmed, and fine grinding of the notch N is performed. After the fine grinding is completed, the wafer W is unloaded from the wafer table 34 and stored in a cassette (not shown).

  As described above, according to the wafer chamfering apparatus and the wafer chamfering method, the abnormality detection sensor of the simple and inexpensive mechanism using air erroneously detects an abnormality such as breakage, dropout, or deformation generated in the notch grindstone. It is possible to confirm without detection.

  Thereby, processing defects and unprocessed parts do not occur on the wafer, and the wafer is not wasted.

  In the present embodiment, the outer peripheral portion is ground before the notch portion is ground. However, the present invention is not limited to this, and the notch portion may be ground before the outer peripheral portion is ground. It can be suitably used.

  In addition, since air is constantly ejected from the normal detection sensor, the air injection port is not clogged with cutting fluid or cutting waste, and it is possible to check the abnormality of the abnormality detection sensor itself. It is possible to confirm the abnormality of the maintenance-free notch grinding wheel that is not affected.

The front view which shows the principal part of the chamfering apparatus concerning this invention. The enlarged view around a wafer table. The side view which showed the outer periphery processing grindstone. The perspective view which showed the structure of the abnormality detection sensor. The perspective view of the abnormality detection sensor at the time of processing a notch with the grindstone for notches. The piping system diagram of an abnormality detection sensor. The top view of the abnormality detection sensor at the time of processing a notch with the grindstone for notches. The flowchart which showed the chamfering method concerning this invention. The top view of a notched wafer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Abnormality detection sensor, 2 ... Arm member, 3 ... Support member, 4 ... Base, 5 ... Pressing member, 6 ... Air sensor part, 7 ... Tube, 8 ... Support | pillar, 9 ... Pressure sensor, 10 ... Chamfering device, 24 ... X table, 28 ... Y table, 33 ... theta spindle, 34 ... wafer table, 52 ... peripheral processing grindstone, 41 ... truing grindstone (truer), 54A, 54B ... periphery precision spindle, 55A, 55B ... peripheral precision grinding wheel (Chamfering wheel), 58 ... Notch fine grinding wheel, 61 ... Notch coarse grinding wheel, 63A, 63B ... Drive device, W ... Wafer

Claims (6)

A wafer table for holding the wafer;
One or more grindstones for grinding the outer periphery of the wafer;
A notch grindstone for grinding the notch portion of the wafer;
Moving means for moving the wafer table relative to the grindstone and the notch grindstone;
A wafer chamfering apparatus, comprising: an abnormality detection sensor which is located in the vicinity of the notch grindstone and confirms whether or not the notch grindstone is abnormal based on a change in back pressure of air to be injected. The abnormality detection sensor includes an air sensor unit that injects air toward the notch grindstone,
An arm member provided with the air sensor at one end;
The wafer chamfering apparatus according to claim 1, wherein the wafer chamfering apparatus includes a support member that supports the arm portion.   When the wafer table is moved by the moving means and the notch portion of the wafer is ground by the notch grindstone, the abnormality detection sensor is supported by the pressing portion provided on the arm portion being pressed by the wafer table. 3. The wafer chamfering apparatus according to claim 1, wherein the member is elastically deformed and the air sensor unit is retracted from the vicinity of the notch grindstone. 4.   4. The wafer chamfering apparatus according to claim 1, wherein the support member has an elastic force and has a cross shape in which two planes intersect each other. 5.   The said abnormality detection sensor confirms the presence or absence of abnormality of this abnormality detection sensor itself by the change of the back pressure when retracted from the vicinity of the notch grindstone. The wafer chamfering apparatus according to any one of the above.   The wafer table is held by a wafer table, and the presence or absence of abnormality of the notch grindstone is confirmed by the change in the back pressure of the air to be sprayed in the vicinity of the notch grindstone of the wafer chamfering apparatus that grinds the outer periphery and notch of the wafer. An abnormality detection sensor is provided so as to be retractable from the vicinity of the notch grindstone, and before the notch portion of the wafer is ground, the abnormality detection sensor confirms whether the notch grindstone is abnormal or not. When grinding, a wafer chamfering method characterized in that the abnormality detection sensor is pressed by the wafer table and retracted from the vicinity of the notch grindstone to check whether there is an abnormality in the abnormality detection sensor itself.

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